This paper develops and tests a model of self-interested judicial behavior to explore the phenomenon of judicial dissents, and in particular what we call ‘‘dissent aversion,’’ which sometimes causes a judge not to dissent even when he disagrees with the majority opinion. We examine dissent aversion using data from both the federal courts of appeals and the U.S. Supreme Court.

Our empirical findings are consistent with the predictions of the model. In the court of appeals, the frequency of dissents is negatively related to the caseload and positively related to ideological diversity among judges in the circuit and circuit size (i.e., the fewer the judges, the greater the collegiality costs of dissenting and therefore, other things being equal, the fewer dissents). We also find that dissents increase the length of majority opinions (imposing collegiality costs by making the majority work harder) and are rarely cited either inside or outside the circuit (reducing the value of dissenting to dissenters). In the Supreme Court, we find that the dissent rate is negatively related to the caseload and positively related to ideological differences, that majority opinions are longer when there is a dissent, and that dissents are rarely cited in either the courts of appeals or the Supreme Court.